A fluid sensor is described in European Patent No. EP 2 508 881 A1. The fluid sensor includes a capacitive measuring device having at least two electrodes and at least one dielectric present between the at least two electrodes. Water molecules penetrate the at least one dielectric as a function of a relative humidity, which causes its permittivity to change. This produces a change in the at least one capacitance between the at least two electrodes. A voltage is applied to the at least two electrodes in order to operate the moisture sensor of European Patent No. EP 2 508 881 A1. In addition, a temperature present in the surroundings is measured by a temperature sensor element and is taken into account in the determination of an output value for the relative humidity.